1. Field of the Invention
This invention relates to a process for the production of organic sulfonic acid oligomers and to the novel compositions produced in the process, particularly sulfonic acid oligomers from straight chain precursor compounds.
2. Description of the Prior Art
It is known to prepare organic sulfonic acids by the reaction of sulfur trioxide with mono-olefinic hydrocarbons in the liquid phase at a temperature below about 100.degree.C., usually below about 50.degree.C., by either contacting the olefin with attenuated sulfur trioxide, that is with gaseous sulfur trioxide which has been diluted with a relatively inert gas, usually air, or with sulfur trioxide which is modified by complexing with an organic ether, acid, acid anhydride, a phosphate ester, or the like. In general, the resulting sulfonate reaction product mixture only contains a minor amount of organic sulfonic acid, usually alkene sulfonic acid, and a major amount of alkane sultones. Additional sulfonic acid can be obtained by hydrolysis of the sulfonation reaction mixture by treatment with aqueous caustic or aqueous mineral acid. When aqueous caustic is employed, the resulting product is a complex mixture which is mainly alkene sulfonate and hydroxyalkane sulfonate. Where acid is employed, the product is a mixture of alkene sulfonic acid and hydroxyalkane sulfonic acid. In the case of the caustic hydrolysate the corresponding sulfonic acid can be obtained by acidification with strong mineral acid and extraction with a suitable organic solvent. The hydroxy sulfonic acid, however, readily revert under acid conditions to sultones with mild heating.
The neutralized sulfonic acids obtained by the use of alpha olefins are excellent surface active agents, and are particularly useful for the production of foamed well circulation fluids. However, aqueous concentrates of these materials tend to solidify and separate into solid and liquid phase mixtures under the temperature conditions encountered in the field.
A more direct process for the production of organic sulfonic acids is desirable for reasons of cost.
A process for the production of organic sulfonic acids substantially free of hydroxy substituents is desirable in order to avoid sultone formation.
An aqueous organic sulfonate detergent concentrate which does not separate into a mixture of solid and/or liquid phases or does so only at very low temperatures is desirable for use in the foamed well circulation fluid art. [See, for example, copending U.S. application Ser. No. 704,832, filed Feb. 12, 1968, now U.S. Pat. No. 3,463,231, issued Aug. 26, 1969. ]